Help!!! with jsp

[ghani]

Hello there Sir

the problem is whenever i m executing the .jsp file in my browser by writting

http://localhost:8080/Simple.jsp

it is giving me an External Servlet Exception message and the exception follows like this:


**********************************************************

javax.servlet.ServletException: null
at org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:481)
at _0002fSimpleJSP_0002ejspSimpleJSP_jsp_0._jspService(_0002fSimpleJSP_0002ejspSimpleJSP_jsp_0.java:73)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:119)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.jasper.servlet.JspServlet$JspServletWrapper.service(JspServlet.java:181)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:393)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:251)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:977)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:196)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:977)
at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2038)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161)
at org.apache.catalina.valves.ValveBase.invokeNext(ValveBase.java:242)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:414)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:975)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:159)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:977)
at org.apache.catalina.connector.http.HttpProcessor.process(HttpProcessor.java:811)
at org.apache.catalina.connector.http.HttpProcessor.run(HttpProcessor.java:890)
at java.lang.Thread.run(Thread.java:484)

----- Root Cause -----

java.lang.NumberFormatException: null
at java.lang.Integer.parseInt(Integer.java:373)
at java.lang.Integer.parseInt(Integer.java:454)
at _0002fSimpleJSP_0002ejspSimpleJSP_jsp_0._jspService(_0002fSimpleJSP_0002ejspSimpleJSP_jsp_0.java:53)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:119)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.jasper.servlet.JspServlet$JspServletWrapper.service(JspServlet.java:181)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:393)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:251)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:977)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:196)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:977)
at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2038)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161)
at org.apache.catalina.valves.ValveBase.invokeNext(ValveBase.java:242)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:414)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:975)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:159)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:977)
at org.apache.catalina.connector.http.HttpProcessor.process(HttpProcessor.java:811)
at org.apache.catalina.connector.http.HttpProcessor.run(HttpProcessor.java:890)
at java.lang.Thread.run(Thread.java:484)

********************************************************

i m trying to execute the jsp file for about 1 month and i still dont know what is wrong. Cause my Tomcat is running just fine i have put all the variable setting in the autoexec.bat file

like

SET JAVA_HOME=C:\JDK1.3
SET CLASSPATH=C:\JDK1.3\LIB\TOOLS.JAR
SET TOMCAT_HOME=C:\TOMCAT

CAN U PLEASE HELP ME WITH THIS PROBLEM I M VERY KEEN TO LEARN HOW TO PROGRAM IN JSP.

THANKYOU

 

[tiz]

Let's see your code...

 

[ghani]

here is my code

this is Simple.html
***********************************************************
<html>
<body>

<p>How many times</p>

<form method=&quot;GET&quot; action=&quot;Simple.jsp&quot;>
<input type = &quot;text&quot; size = &quot;2&quot; name = &quot;numtimes&quot; >
<inut type =&quot;submit&quot;>
</form>
</body>
</html>
************************************************************


and now this is Simple.jsp

***********************************************************
<@% page language=&quot;java&quot; %>


<html>
<body>

<p><% int numTimes = Integer.parseInt(request.getParameter(&quot;numtimes&quot);
for(int i=0;i<numTimes;i++){

%>

<% }
%>
</p>


</body>
</html>

***********************************************************

now i have saved both of theses files in the webaps\root of tomcat and i dont now why it is not working

it is just a simple program

thanx

 

[tiz]

Hi,

Couple of things wrong with this ...

Firstly the structure is wrong and you have '%>' tags and '}' tags in the wrong place.

Secondly, the reason you're getting 'null' when you call it with

http://localhost:8080/simple.jsp

is because in your code you are expecting a parameter to be passed in called numtimes which has to be an integer:

int numtimes... getParameter("numtimes");

If this parameter is not passed in, it tries to store null in an int which throws an exception before you can trap it. Try

http://localhost:8080/simple.jsp?numtimes=5

and then your for..loop will iterate 5 times.

Here is an example for you which should explain what you're doing wrong:

<% String param = request.getParameter(&quot;numtimes&quot;);

   int NumTimes = 0;

   if(param != null) {
	NumTimes = Integer.parseInt(param);
	for(int i=0;i<NumTimes;i++){   
	  out.print(i);
         }
   } else {
	out.print(&quot;You must specify the numtimes parameter!&quot;);
   }
%>

Bye for now,

Tiz --
Tim <tim@planetedge.co.uk>

 

[cwinans]

It looks to be an error when you attempt to parse an int from the form parameter

try this:

try {
int numTimes = Integer.parseInt(request.getParameter(&quot;numtimes&quot);
}
catch(NumberFormatException fx) {
// error parsing the string
out.println(&quot;Error while attempting to parse int from string&quot;
}
I hope this helped! ;-)
- Casey Winans